Snow blowers range from the very small, capable of removing only several inches (a few cm) of light snow in an 18 to 20 inch (45 to 50 cm) path, to very large, mounted onto heavy duty winter service vehicles and capable of moving 10 foot (3 m) wide swaths of heavy snow up to 6 feet (2 m) deep. Snow blowers can generally be divided into two classes: single stage and two stage.
Single-stage snow blowers use a single high-speed impeller to both move the snow into the machine and force it out the discharge chute. The impeller is usually in the form of two or more curved plastic paddles that move snow towards the centerline of the machine where the discharge chute is located. Single-stage snow blowers usually are light duty machines. Small electric machines can actually be picked up to chew away deep snow banks a layer at a time.
One exception to the "single-stage snow throwers are small" rule are the enormous single stage rotary snow throwers used by railroads to clear tracks in mountainous areas. These rotary snowplows use one or two very large impellers that can span the entire width of the train and typically discharge to the side
By comparison, two-stage snow blowers have one or more low-speed metal augers that break up the snow and move it into a separate high-speed impeller (sometimes called the fan). The impeller 'blows' the snow out the discharge chute with considerable force. All but the lightest-duty snow throwers are typically two-stage machines.
Two-stage snow blowers range in power from a few horsepower to very large machines powered by diesel engines of over 1000 horsepower (750 kW). The large machines are used for clearing roadways and airport runways. These are capable of removing large amounts of snow quickly. Some municipalities use larger snowblowers to clear snow from streets after a snowfall, often by blowing the snow into trucks which haul it away.
Two-stage machines for home use are usually self-propelled, using either large wheels equipped with tire chains or, in some cases, tracks. These are usually single-purpose machines, though some are detachable front ends that can be replaced with other implements, such as a rotary tiller.
The auger drive is usually equipped with a shear pin. If a major jam occurs in the auger, this pin will break. This controlled failure prevents damage to the auger drive gears. Once the pin has failed it must be replaced before the machine can be used again, this is generally a relatively simple process.
One problem with the design of the snowblower is that snow can build up in the auger, jamming it and stalling the motor. This is complicated by the fact that the auger may twist before applying enough resistance to the motor to stop it. If the jam is cleared with a hand, it is possible for the auger to return to its natural shape suddenly and with great force, possibly injuring the user; snowblowers are a leading cause of traumatic finger amputations. The correct procedure is to stop the engine, disengage the clutch and then clear the jam with a broom handle or other long object.
Most modern machines mitigate this problem by including a safety system known as the "Dead man's switch" (which may be electrical as implied or mechanical in design, such as a lever), to prevent the mechanism from rotating when the operator is not at the controls. In some jurisdictions, this is a mandatory requirement.
Pollution from gas-powered groundskeeping equipment is a significant source of air pollution. US emission standards specifically limit emissions from small engines. Electric models produce no emissions at the point of use, but may shift pollution to power plants. Emissions may still be reduced by the use of renewable energy in grid generation, or because central power plants generally must have stricter emissions control equipment installed.
Though Robert Carr Harris of Dalhousie, New Brunswick patented a "Railway Screw Snow Excavator" in 1870, the invention did not advance. Various other innovations also occurred. However, it is Arthur Sicard (December 17, 1876 - September 13, 1946) who is generally credited as the inventor of the snow blower. Arthur Sicard was a mentally challenged boy who lived on a farm when he was a boy, and used to sell milk. Finding that it was hard to transport his milk and eggs due to the snow, he dreamed up an idea for a machine that would blow snow and clear up roadways. In 1925 Sicard completed his first prototype, based on a concept he described in 1894. He founded Sicard Industries in Sainte-Thérèse, Quebec and by 1927 his vehicles were in use removing snow from the roadways of the town of Outremont, now a borough of Montreal. His company is now a division of SMI-Snowblast, Inc. of Watertown, New York, USA, as well as a Canadian operation, Sicard SSI Group, Inc. in Knowlton, Quebec.